Form/fill/seal machines are old in the art. However, the ability to use them for packaging resiliently compressible articles, such as diapers, in a compressed state has been a recent development. U.S. Pat. No. 4,592,193 to Gustavsson, for example, discloses an apparatus which compresses articles by means of a pair of converging belts above and below the articles. Compressed articles are indexed through a compression section and into a parallel conveyor section, which maintains the articles compressed by top and bottom belts and is cantilevered into a film tube forming system. A film tube forming system is located around the parallel conveyors. The film tube edges are brought together and sealed where they overlap. A drive connection between the film and the parallel conveyors is provided to advance the film when the conveyors index. At the discharge end of the parallel conveyor, a means for cross-sealing and cutting the film tube is provided. Immediately thereafter, a discharge conveyor is located. The purpose of the discharge conveyor section is to maintain the articles compressed after they are released into the film tube, which has a fresh overlap seal. The discharge conveyor section provides time for the seal to cool and gain sufficient strength to maintain the articles compressed. The system of Gustavsson is believed to be slow because the entire system indexes forward one article at a time. Also, Gustavsson requires a separate discharge conveyor section to regrip the compressed articles after they are released into the tubing.
U.S. Pat. No. 3,523,628 to Lee et al. discloses an article compressing apparatus for a stack of disposable diapers. Compression occurs between a pair of converging endless belts which discharge the stack into a holder, such as a pair of spaced jaws which hold the stack compressed as a paper sleeve wrapper is disposed about the stack to hold it in a compressed state. The stack of diapers is compressed to about one-half of its original thickness in a continuous process. In another reference.
U.S. Pat. No. 5,022,216 to Muckenfuhs et at., a method and apparatus are disclosed for transferring a compressed stack of diapers into a preformed bag. However, neither of these references deal with the problem of forming and sealing a continuous plastic film tube while a stack of articles is being loaded into it.
U.S. Pat. No. 4,722,168 to Heaney discloses a film tube forming and sealing system. A film tube is formed into a generally rectangular shape, having its two edge portions formed into downwardly extending fins. Finwheels grip the downwardly extending adjacent pair of film edge fins. The middle pair of finwheels is preferably heated to effect sealing of the edges together in a continuous longitudinal seal. However, as in most other form/fill/seal machines, the articles are not resiliently compressed, so that there is again no concern with forming and sealing a continuous plastic film tube while a stack of articles is being loaded into it.